Britain's supermarkets could face a government inquiry for raising food prices above the rate of inflation, City experts have warned.

Investment bank UBS predicted on Monday that the supermarket sector could be investigated for pushing up UK food prices faster than in the rest of Europe. UBS suggested that major retailers may be increasing their profit margins from food sales, which could prompt politicians to take action.

"UK food prices are rising more rapidly than most other OECD economies' food prices and have significantly outstripped food retailers' cost inflation," analysts at the Swiss bank said in a report. "This could allow UK politicians to suggest that food price inflation is 'unfair' or 'excessive'."

UK food inflation hit an annual rate of 4.6% in February, its highest level for 18 months and much higher than the eurozone average of 1.5%. The rising cost of food on the shelves is one factor that has driven overall UK inflation to twice the official target.

UBS said: "After two years during which processed food prices have been rising more than 50% faster than the associated costs, and at a time when food prices have heightened political importance, it seems unlikely that this position will continue to be ignored."

Retailers have blamed the weaker pound for pushing up food import costs, and deny allegations that they are "ripping off" the public. The British Retail Consortium argued that supermarkets are actually protecting customers from the full impact of global food inflation.